Such a network could also give emergency first-responders a reliable channel if a natural disaster destroys communication towers or access points.

The system uses a vehicle's onboard computer, GPS, low-cost sensors, custom software written by the team, and existing wireless channels.

In recent experiments, the researchers used the standard protocol that allows laptops, for example, to connect wirelessly to the internet. The typical range is 100-300 metres.

In the near future, vehicles will switch to the Dedicated Short Range Communications standard being developed by the US Department of Transportation.

This signal, which has a range of up to a kilometre, will allow high-speed communications between vehicles or between vehicles and the roadside.

The team's software locates its own car and the cars it wants to talk to, selects the strongest signals, determines if any of the drivers should have priority (emergency workers might, for example), and organises the data being exchanged.

For now, cars within a couple to a few hundred metres of each other can exchange data, but the information can hop from one car to the next across the entire network, which could span kilometres.

Sharing maps

If a car needs information directly from the internet, it needs to access a fixed communication tower or hotspot or it must talk to other cars that have accessed the internet.

"In some applications a car just needs internet content, say a local map or picture. Then, the car can get the data secondhand from another car that was earlier connected to the internet and happened to have downloaded that map or picture," says Professor Mario Gerla, who heads the UCLA Network Research Lab.

Earlier this month, team members drove around the Los Angeles area to determine how many open access points a car could tap into at any given time. They discovered there were, on average, 30.

Mobile networks

Other groups are also working on mobile networks, but Pau and Gerla see three main advantages to their approach.

First, thanks to a collaboration with the Los Alamos National Laboratory in New Mexico and Italy's Istituto Boella in Turin, the researchers can simulate realistic traffic scenarios on a very large scale and can thus finetune the software.

Second, they are also testing distinct types of mobile network patterns, such as those designed specifically for emergency workers.

Sharing with other researchers

Third, other mobile networking groups will benefit. The group will be opening up their test bed to the scientific community, giving other research groups the opportunity to test their own applications.

"Automakers have their own simulations, but these simulations are internal and it's very unlikely that they would be made available to the academic community," says Dr Liviu Iftode, associate professor of computer science at Rutgers University.